It is a curious fact and a great disadvantage that as long that there is no clear loss of function, there is no alarm mechanism in the retina and optic nerve that informs about regional malnutrition. And even when there is loss of function the symptoms may be discrete and difficult to define: open angle glaucoma is a good example. It may be a great disadvantage also that our undestanding of the metabolic requirements of the retina under different light conditions is poor; there may be illuminations and other situations that should be avoided by patients with glaucoma, diabetic retinopathy and other diseases characterized by insufficient nutrition of the retina and optic nerve. Finally, it seems as a major problem in the pharmacological treatment of glaucoma that so little is known about the normal control of aqueous humor formation and drainage in primates; there are good reasons to suspect that information from lower species may be very misleading due to differences in control mechanisms and anatomy. The aim is to study the metabolic consequences in the optic nerve and the different layers o1 the retina of different kinds of light and to deflne the situation that is the most stressful. This aim is also to analyze whether in that situation the retina and optic nerve become more susceptible than normal to elevations of the intraocular pressure and to moderate hypoxia. The deoxyglucose method described by Sokoloff for studies on regional glucose consumption in the brain will be used in these studies. Under normal conditions the uptake of labelled deoxyglucos' reflects the activity of the tissue. Under conditions of moderate partial underperfusion it can be used to trace regions with enhanced glucose consumotion due to anerobic glycolysis. After i.v. injection of deoxyglucose labelled with tritium or 14C blood samples are collected and the animal is put to death after 40 minutes. Autoradiographs are made of sections of the whole head and analyzed with computerized microdensitometry. Another aim is to define the mechanisms involved in the control of the rate of aqueous humo formation and drainage in monkeys and ascertain what possibilities there may be to manipulate these mechanisms in the treatment of glaucoma. Aqueous humor formation is calculated fron data for the dilution of radioactively labelled albumin perfused through the anterior chamber flow to blood Is calculated from data for blood actlvlty and uveoscleral flow Is calculated as the dlfference betweeen rate of formation and the flow to blood.